Effect of simulated hail damage on yield and quality of Russet Burbank potatoes

The yield and quality response of Russet Burbank potatoes to simulated hail damage was dependent upon the amount of damage and on the growth stage at which the damage occurred. Plots of Russet Burbank potato plants were subjected to 0%, 10%, 25%, 50%, 75%, or 100% defoliation at 3, 5, 7, 9, 11, or 14 weeks after emergence. A motorized flail was used to simulate the complex damage that occurs during a natural hail storm. Early season simulated hail damage, when the plants were mainly vegetative, caused yield losses proportional to the degree of damage. Simulated hail damage during the early phases of tuber growth caused minor yield losses (< 5%) at low defoliation levels but severe losses at the higher levels with proportional loss of tuber quality. Defoliation later in the season resulted in progressively less reduction of both yield and quality. At or near maturity, late season simulated hail damage caused insignificant losses unless the stems were damaged enough to prevent nutrition and carbohydrate translocation into the tubers.     

The market for consultants in the Idaho potato industry

Idaho potato growers and consultants were surveyed to analyze the market for consulting services. Potato growers use three types of technical consultants to improve the profitability of their operations: public consultants, industry consultants, and independent consultants. Growers rated independent consultants most reliable and were most satisfied with industry consultants. Growers rated their own records as the most valuable sources of information for making production, marketing and financial decisions. Consultants were most widely used in production decisions. Pest identification and control was the most commonly offered service by Idaho consultants. Growers who were satisfied with previous use of independent consultants were more likely to continue to use consulting services. Consultants are generally providing the types of services demanded by growers. The largest unmet needs are for consulting services in marketing, business planning and storage management.     

Analysis of <Emphasis Type="Italic">Potato Mop-Top Virus</Emphasis> Survival Probability in Post-Harvest Storage

Potato mop top virus (PMTV) induced necrosis can cause tuber quality loss at harvest and storage. Stored potatoes help maintain a constant supply of potatoes to the market and processing industry. PMTV-induced necrosis continues to develop during storage and appropriate timelines are needed for growers to make marketing decisions of their potatoes before incurring any significant quality losses. Survival analysis was used to estimate the time to event occurrence (PMTV-induced necrosis) in four (red-, russet-, white-, and yellow-skinned) potato market types across six post-harvest assessments conducted over two years. At each assessment the presence and absence of PMTV-induced necrosis was recorded and probability of tuber survival was estimated. Survival curves were significantly different among the four market type potato cultivars (Log-Rank test, P < 0.0005). Red- and russet-market type cultivars showed low and high survival probability, respectively, demonstrating that red cultivars need priority marketing. The survival probabilities decreased with increased storage time during both years, indicating that PMTV-induced necrosis development is dependent on potato cultivar and post-harvest storage. The median (50% of tubers with symptoms) survival times were estimated as 167 and 214 days for red- and other market type potato cultivars. The information from this study could potentially help growers regulate storage times for their cultivars to minimize tuber quality loss due to PMTV-induced tuber necrosis.     

Comparison of water trap pans and leaf counts as sampling techniques for green peach aphids on potatoes

Green peach aphid populations were monitored by using water trap pans and by taking leaf samples in 38 southwestern Idaho potato fields from 1972 to 1975. Numbers of winged aphids in trap pans were correlated with populations of aphids developing in adjacent fields but were not predictive of future population trends. Trap pan data are, however, useful in alerting growers to the possibility of damaging field populations which exist in a field at the time of sampling.     

Production of seed potatoes in Cyprus: the effects of roguing and planting date on the spread of potato leaf roll virus,tuber yield,and infestation by potato tuber moth

Summary Field experiments during 1984–6 tested the effects of planting date on the development of aphid infestations and the spread of potato leaf roll virus (PLRV) in rogued or unrogued plots of potatoes, cv. Spunta. Plantings were made each month from December to April, the customary time for planting being February. Aphid infestation in early-planted plots was severe throughout the growing season; plots planted in February were also severely infested early in the growing season but the populations later gradually declined to undetectable levels. Nevertheless, the incidence of PLRV in the latter plots was as high as in those planted in December-January. Late-planted crops escaped aphid infestation and PLRV infection, either in part (March planting) or completely (April planting). Such crops, however, were uneconomical due to poor yields and heavy losses from potato tuber moth infestation. Roguing significantly reduced the spread of PLRV in all years but its interaction with planting date was insignificant.     

The need for international research programmes on some potato pathogens

Summary Growers are being faced with a conflic between the effects of specialization on increasing pest and disease problems (particularly late blight, Colorado beetle, cyst nematodes and tuber moth), and public opinion that will force them to reduce the use of pesticides. For this disease and these pests international research programmes are needed to develop parental lines and cultivars with durable resistance that can be used world-wide. This account is based on ‘The potato in world perspective’, a paper read at the First World Potato Congress held on 8–10 July 1993 in Charlottetown, Prince Edward Island, Canada.     

Current control methods for diamondback moth and other brassica insect pests and the prospects for improved management with lepidopteran-resistant Bt vegetable brassicas in Asia and Africa

The diamondback moth (DBM), Plutella xylostella (L.), remains a major pest of brassica crops worldwide. DBM has been estimated globally to cost US$ 1 billion in direct losses and control costs. Chemical control of this pest remains difficult due to the rapid development of resistance to insecticides and to their effect on natural enemies. These problems are especially severe in South Asia and Africa where lack of knowledge, limited access to newer and safer insecticides, and a favourable climate result in DBM remaining a serious year-round pest which substantially increases the cost and uncertainty of crop production. Despite these problems, application of synthetic insecticides remains overwhelmingly the most common control strategy. Biologically-based efforts to control DBM in Africa and Asia have focused strongly on parasitoid introductions. However, despite the identification and deployment of promising parasitoids in many regions, these efforts have had limited impact, often because farmers continue early-season spraying of broad-spectrum insecticides that are lethal to parasitoids and thus exacerbate DBM outbreaks. A significant driver for this pattern of insecticide use is the presence of aphids and other pests whose appearance initiates inappropriate spraying. Despite often extensive training of producers in farmer field schools, many growers seem loath to discard calendar or prophylactic spraying of insecticides. The introduction of an IPM technology that could replace the use of broad-spectrum insecticides for DBM and other key Lepidoptera is crucial if the benefits of parasitoid introduction are to be fully realised. The deployment of DBM-resistant brassicas expressing proteins from Bacillus thuringiensis could help to break this cycle of insecticide misuse and crop loss, but their deployment should be part of an integrated pest management (IPM) package, which recognises the constraints of farmers while addressing the requirement to control other Lepidoptera, aphids and other secondary pests.     

Comparative Analysis of Irish Potato (<Emphasis Type="BoldItalic">Solanum tuberosum</Emphasis> L.) Production in the Farming Sectors that Emerged from Zimbabwe’s Radical Land Reform of 2000

Irish potato production in Zimbabwe can be traced back to the early 1900s. Large-scale commercial farmers dominated production until the early 2000s. Potato is the most important horticultural crop and has been declared a strategic national food security crop in 2012. In 2000, the Fast Track Land Reform Programme completely restructured commercial agriculture and potato farming. A product of the agrarian reforms, the A2 and A1 resettlement growers, started growing potato. The A1 resettlement model has individually owned cropping land and shared grazing, while A2 resettlement comprises of self-contained farm units. A survey was conducted to characterise potato growers, mainly to understand the current potato production systems and to assess the impact of the landmark reform programme on potato farming. Four production systems, large-scale commercial, communal area, A2 resettlement and A1 resettlement, were identified, and two main growing agro-ecological zones, the Highveld and Eastern Nyanga Highlands. In 1961–2013, significant positive trends for annual planted area, average yield and total production were observed. In terms of yield, Zimbabwe is fourth in southern Africa with an average yield of 17 t ha^?1 in the 2009–2013 period. Large-scale commercial and A2 resettlement systems were well-mechanised, and growers owned large land holdings ranging from an average of 165–1600 and 31–390 ha across the different areas, respectively, with average potato areas of 11 and 8 ha, respectively. A1 resettlement and communal area growers owned an average of 4 and 3 ha cropping area, respectively, with average potato areas of 0.4 and 1.1 ha, respectively. Input use was significantly different among the production systems. High synthetic fertiliser and biocide use was observed.     

Climate Change and Potato Production in Contrasting South African Agro-Ecosystems 2. Assessing Risks and Opportunities of Adaptation Strategies

This study aims to assess the risks and opportunities posed by climate change to potato growers in South Africa and to evaluate adaptation measures in the form of changes in planting time growers could adopt to optimise land and water use efficiencies in potato, using a climate model of past, present-day and future climate over southern Africa and the LINTUL crop growth model. This was done for distinct agro-ecosystems in South Africa: the southern Mediterranean area where potato still is grown year round with a doubling of the number of hot days between 1960 and 2050, the Eastern Free State with summer crops only and Limpopo with currently autumn, winter and spring crops where the number of hot days increases sevenfold and in future the crop will mainly be grown in winter. A benefit here will be a drastic reduction of frost days from 0.9 days per winter to 0. Potato crops in the agro-ecosystems will benefit considerably from increased CO₂ levels such as increased tuber yield and reduced water use by the crop, if planting is shifted to appropriate times of the year. When the crop is grown in hot periods, however, these benefits are counteracted by an increased incidence of heat stress and increased evapotranspiration, leading in some instances to considerably lower yields and water use efficiencies. Therefore year-round total production at the Sandveld stabilizes at around 140 Mg?ha^?1 (yield reduction in summer and yield increase in winter), increases by about 30% in the Free State and stays at about 95 t?ha^?1 at Limpopo where yield increase due to CO₂ is annulled by a shorter growing season. When the crop is grown in a cool period, there is an additional benefit of a reduced incidence of cold stress and a more rapid canopy development in the early stages of crop growth. In all three areas, potato growers are likely to respond to climate change by advancing planting. In Limpopo, a major benefit of climate change is a reduction in the risk of frost damage in winter. The relevance of these findings for potato grown in agro-ecosystems elsewhere in the world is discussed.     

安溪茶园冰雹灾害灾后救护技术专报

根据安溪县感德、桃舟、剑斗、祥华等4个乡镇茶园冰雹灾害的不同茶树种植区域、茶园类型、受害程度及气象条件等具体情况,有针对性地采取及时清雹松土、分类整枝修剪、分期施用肥料和病害防范等救护技术措施,确保茶树成活,减少灾害造成的损失。     

马铃薯氮素营养状况的SPAD仪诊断

以马铃薯品种克新1号为材料,研究了叶片SPAD值、叶片全氮含量、叶绿素含量以及块茎产量随供氮水平的变化规律及相互关系,旨在为使用叶绿素仪进行马铃薯无损伤氮素诊断和推荐施肥奠定基础。研究结果表明,从马铃薯苗期到块茎淀粉积累各个生育阶段叶片的SPAD测定值均与马铃薯叶片含氮量呈显著正相关关系。除苗期外,块茎形成期、块茎膨大期、淀粉积累期的马铃薯叶片含氮量和叶片SPAD值随土壤施氮量的变化均表现为线形加平台的模式。因此马铃薯块茎形成期后叶片的SPAD读数可揭示马铃薯的氮素营养状况。统计分析结果还表明,叶片SPAD值与块茎相对产量呈线形加平台的数量关系模式,据此确定了应用叶绿素仪SPAD-502进行马铃薯推荐施肥的SPAD临界值为块茎形成期47.3、块茎膨大期45.1、淀粉积累期40.2。     

Impact of Canopy Destruction from Simulated Hail on Potato Yield and Economic Return

Insurance against hailstorm-inflicted losses to potato crops is crucial for producer risk management. Insurance providers need regionally specific information on which to base estimates of hail damage. The objective of the research reported here was to determine the effects of a range of simulated hail defoliation treatments, low (33%), medium (66%), and high (99%), relative to an untreated control (0%) on yield and grower economic returns from one medium- and one late-maturing potato variety (‘Russet Norkotah TX278’ and ‘Ranger Russet,’ respectively) at three growth stages (tuber initiation, early bulking, and late bulking) in the Columbia Basin of Washington. Plants within the 33% and 66% treatments were defoliated by sweeping a garden rake with 16 solid, curved tines through the canopy of each treatment row several times until plants exhibited the desired defoliation level. Tuber initiation and early bulk plants within the 99% treatment were essentially mowed to ground level. Intensity of defoliation and stage of growth had significant, interacting effects on grower returns. Gross return and yield for both varieties at each growth stage were significantly reduced by 99% defoliation; these effects were mediated by the effects of defoliation on tuber size distribution. Total yield and gross return experienced the largest declines at early bulk compared with tuber initiation and late bulk defoliation in both varieties. When 99% of the early bulk foliage was removed, Russet Norkotah TX278 gross return and yield were reduced to 14% and 38%, respectively, of the values for the non-treated control, and Ranger Russet gross return and yield were reduced to 30% and 51% of control values, respectively. Defoliation of 99% at all growth stages significantly reduced overall market yield compared to controls for both varieties. However, tuber size distribution was most affected by 99% defoliation at early bulk. Severe defoliation (99%) at tuber initiation significantly delayed vine senescence in both varieties. The results of this study suggest that insurance adjusters should take into account the combined influence of growth stage and defoliation level when hail damage occurs.     

Assessment of pesticide use in the U.S. potato industry

Pesticide use in US fall crop potato production was surveyed for the years 1990 to 1994. The purpose of the study was to provide information about the relative importance of each pesticide and potential alternatives. The objectives were to: (1) inventory pesticides used on potatoes, (2) rank the target pests and (3) estimate the economic value of the major pesticides. Extension specialists working on potatoes in twelve states provided the main source of survey data. The most commonly used pesticides in four categories were: fungicide —chlorothalonil, insecticide —methamidophos, herbicide —metribuzin, and “other” -diquat. The most frequent target pests were: early blight (Alternaria solani), late blight (Phytophthora infestans), aphids (primarily Myzuspersicae), Colorado potato beetle (Leptinotarsa decemlineata), lambsquarter (Chenopodium album), and pigweed (Amaranthus spp.). The pesticides that provided the most annual value to potato growers were methamidophos ($281 million), diquat ($86 million), metribuzin ($81 million), CIPC ($56 million) and esfenvalerate ($52 million).     

Integrated pest management of potato tuber moth in field and storage

Summary The potato tuber moth (PTM),Phthorimaea operculella (Zeller), is one of the most damaging pests of potatoes in field and storage. Tuber moth is active throughout the year in North Africa but is most active from late April to early August. Many cultural practices that are used by farmers to improve the yield and quality of potato can also limit the development of the potato tuber moth and minimise damage to tubers. As the farmers gain more experience with both agronomic practices and chemical insecticides, they are likely to rely more heavily on cultural practices and less on insecticides to manage PTM. Measures which could keep PTM damages in rustic and diffuse light stores to a minimum are discussed. Ideally, there is need to integrate pest management in potato fields and stores. PTM control in stores was found to be more effective if infestation in fields was kept to a minimum. Low infestation at harvest and rapid handling of the potatoes going into store established good initial storage conditions and decreased the likelihood of post-harvest losses. Biological insecticides in particular were more effective in preventing losses by insects in stores in cases where the initial level of infestation was relatively low.     

Bird damage to select fruit crops: The cost of damage and the benefits of control in five states

Fruit loss to birds is a long-standing and costly problem for many producers. We conducted a survey of Honeycrisp apple, blueberry, cherry, and wine grape growers in California, Michigan, New York, Oregon, and Washington to estimate costs of bird damage and benefits of bird damage management. We also assessed grower perceptions of impacts on profits and effectiveness of bird management techniques. Current yield-loss estimates provided by growers and market price data were used to monetize current bird damage in each crop and growing region. Data on expected damage without management were used to estimate the benefits of bird damage management as it is currently being employed in the different crops and growing regions. We estimated that current bird damage costs per hectare ranged from $104 in Oregon tart cherries to $7267 in Washington Honeycrisp apples. Estimated benefits of bird management ranged from $299 per hectare in Oregon tart cherries to $36,851 in California blueberries. Aggregate bird damage in the five crops and states was estimated at $189 million, and the aggregate benefits of managing that damage were estimated at $737 million to $834 million. Growers viewed most techniques for bird damage management as ineffective, or only slightly effective, and a majority of blueberry and sweet cherry growers viewed bird damage as having a significant impact on profits. Enhancing the effectiveness of bird damage management would increase both the efficiency and profitability of fruit production.     

马铃薯块茎还原糖含量与钾代谢关系的研究

通过田间试验和室内分析测定,对马铃薯块茎低还原糖形成的生理基础与钾代谢的关系进行了初步研究。结果表明,马铃薯块茎中还原糖含量随生育进程逐渐减少;叶片、茎秆和块茎中含K量随生育进程呈降低的变化趋势;克新1号茎秆含钾量与其块茎还原糖含量、夏坡蒂块茎中含钾量与还原糖含量相关性均达到了极显著水平。因此,可以把克新1号茎秆中的含钾量和夏坡蒂块茎中的含钾量作为油炸食品加工原料品质预测和新品种选育的重要生理指标。     

The effect of combined infestation by cereal aphids (Macrosiphum avenae (Fabr.) (Sitobion avenae) and Rhopalosiphum padi (L.)) and cereal leaf beetles (Oulema melanopus (L.)) on their population development and on yield of winter wheat

Previous clarification of the relationships between insect populations and damage by cereal pests has enabled the effect of combined pest infestation on the yield of winter wheat to be analysed more thoroughly. The cereal aphids Macrosiphum avenae (Fabr.) (Sitobion avenae) and Rhopalosiphum padi (L.), each in combination with the cereal leaf beetle Oulema melanopus (L.), were investigated in pot trials which enabled interactions between the combined pest populations to be studied also. Although intraspecific competition was observed for each pest population, there was no interspecific adverse effect of density on population increase. With increasing population densities of the pests in combination, the relative contribution of each species to the combined yield losses decreased. Consequently, there was no summation of individual losses, but a reduction of up to 24·3%. The ability of the cereal plant to compensate for losses may be responsible for this ‘buffering effect’, which apparently is attributable to increased dry-matter production in the presence of large combined pest populations. These results suggest that the existing economic thresholds relating to the effects of cereal aphids and cereal leaf beetle on yields of winter wheat require modification.     

华北一季作区马铃薯病虫害种类、分布与为害

2009-2010年通过田间5点取样对华北一季作区马铃薯病虫害进行普查。结果查得病害有花叶病毒病C表现为花叶症的所有病毒病）、卷叶病毒病、紫顶萎蔫病、早疫病、晚疫病、黑痣病、炭疽病、叶枯病、枯萎病、环腐病、黑胫病、疮痂病共计12种。查得害虫10种：金针虫、蛴螬、地老虎、蚜虫、二十八星瓢虫、芫菁、双斑萤叶甲、草地螟、牧草盲蝽、马铃薯跳甲。明确了上述病虫的分布和为害程度,许多病虫是该地区目前严重威胁生产的问题。     

Freezing behavior of potato (Solanum tuberosum) tubers in soil

Volunteer potatoes are a major weed problem in potato rotations in regions with mild winter soil temperatures. Freezing dynamics of potato tubers in air have been previously reported, but freezing dynamics of tubers in soil may differ due to ice nucleation sites and soil water associated with soil. Laboratory experiments conducted in hydrated and dry soil columns and field experiments were conducted to determine cold temperatures required to kill potato tubers in soil. Potato tubers in air-dried soil columns exposed to decreasing temperatures typically supercooled to ?3 to ?7 C before exhibiting a distinct exotherm, which stabilized at ?1.4 to ?1.5 C, representing the freezing point of tubers. Tubers that were supercooled and removed from the cold environment before experiencing this exotherm were able to sprout and had no visual symptoms of freezing injury, whereas tubers that experienced the exotherm were nonviable and unable to sprout. Tubers in soil columns hydrated to 7% SWC supercooled much less than tubers in dry soil and exhibited an exotherm that stabilized near ?1.9 C. Tubers exposed to temperatures near the tuber-freezing point (?1.4 to ?1.9 C) for periods of 1 min to 24 h, but not undergoing an exotherm, exhibited varying degrees of injury, which increased with time of exposure. Tubers held at ?1.0 C for 4 to 24 h were unharmed and able to sprout similar to controls. In field trials conducted from 1993 to 1999 in the Columbia Basin of Washington, tubers buried at shallow depths (5 cm) were much more likely to experience lethal cold temperatures than tubers buried deeper. In general, when minimum soil temperature at tuber depth reached ?1.5 to ?1.9 C or lower, some tuber mortality occurred and when soil temperature at tuber depth reached ?2.8 C or lower, extensive tuber death occurred. Monitoring of winter soil temperatures by depth in potato- growing regions could be used to predict severity of volunteer potato for the subsequent growing season.     

Alaska red: A general purpose,productive, red-skinned potato

‘Alaska Red’ is the first red-skinned potato bred and selected in Alaska as a clone suitable for the fresh potato market. Its parents are Alaska Clone 11-57-1-59 and ‘Red Beauty’. It is a high yielding, medium specific gravity potato with uniform skin and eye basin color, shallow eyes, uniform oval-to-flattened shape and is very attractive. The flesh is snowy white and remains white after boiling. Alaska Red keeps well in storage at 38°F (3.3°C). Scab of the tubers is the only disease that has been observed. In this subarctic region, flowers abort in the early bud stage. Red-skinned potato varieties available to Alaskan growers for the past quarter century have been unsatisfactory due to one or more of the following characteristics: low dry matter content, poor yield, uneven skin pigmentation and internal or external tuber cracking. Although consumers buy far less red than white-skinned potatoes, the demand brings Florida “reds” to Alaska as well as “reds” from other regions so that there is a year round outlet. Imported “reds” never approach the high quality of Alaskan grown “reds”. During the screening of seedlings, ‘Red Beauty’ was selected as a parental line because of its excellent conformation, skin color and eye arrangement. Low yield and shatter cracking made it unsuitable for commercial production. Alaska Red is a selection from seedlings of the cross Ak. 11-57-1-59 and Red Beauty made in 1965 and is the first red-skinned potato released from Alaska’s potato breeding. It was first evaluated by potato growers in 1972 and released in 1976 by the Agricultural Research Service, United States Department of Agriculture, Box AE, Palmer, Alaska 99645.